Telephonic systems



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TELEPHONIC SYSTEMS Attorney Feb. 11, 1964 F. P. GOHOREL TELEPHONICSYSTEMS 19 Sheets-Sheet 15 Filed Jan. 8, 1959 l n venlor F 2 fab aka Attorne y Feb. 11, 1964 F. P. GOHOREL 3,121,141

TELEPHONIC SYSTEMS Filed Jan. 8, 1959 19 Sheets-Sheet 16 Inventor A3gaflanfl A Home y l9 Sheets-Sheet 19 Filed Jan. 8, 1959 QwQI vwE 501 moE NQE In uen for FF. gb alfL A tlorn e y United States Patent 3,121,141TELEL HONIC SYSTEMS Fernand Pierre Gohcrel, Antony, France, assigner tointernational Standard Electric tier-partition, New York,

N31, a corporation of Delaware Filed San. 3, i959, der. No. 735,653Claims p iority, application France 34, E53 17 Qlaims. (Cl. 179-423)This invention is directed to improvements in automatic telephoneswitching systems and deals more particularly the problems of relievingthe overload of telephone networks. The number of subscribers increasessteadily; in the big cities, the number of incoming lines in an exchangeis very high which leads to a certain number of dilficulties andparticularly the overloading of the income distributors. Hence, it is ofgreat interest to scatter all over the telephone network unstaifed smallexchanges or concentrators linked together by means of a small number oflines which connect them to a more important office. The subscriberslines are thus shorter, their concentration is lower, which yields anefficient saving. On the other hand, the elements used in automaticswitching have reached a sufiicient degree of reliability to warranttheir use in small exchanges Without supervision. Whatever be theimportance and the density of a network, the curtailing of expenses intelephone leads is always importent and the use of automaticconcentrator equipments applies to small networks as well asintermediate and large ones.

in prior art disclosures, an automatic switching system has beendescribed using cross-bar switches with one or more common controldevices (markers) in each selection stage. These systems call forelements which have s'n wn great stability and need very littlemaintenance; some of their design characteristics allow these systems tobe easily decentralized, which makes them suitable for the relieving ofthe network overload.

A feature of the invention is to provide a telephone switching systemwith exchanges and distant concentrators, formed by final selectorshaving a local part located at the exchange, and a distant part locatedat the concentrator, the local part including all the elements of ausual final selector except the talking wires which are in the distantpart, and operating in the same manner as in the case of a localsubscriber, arrangements being provided to transmit from theconcentrator to the exchange the identity of the calling subscriber andto mark his position on the outlets of the final selector local part,arrangements being also provided to transmit from the exchange to theconcentrator the information relative to the position of the finalselector local part, so as to set the distant part on a similarposition.

The fact that the selection process is carried out at the exchangewithout any difiierence between a local and a distant subscriber bringsseveral advantages. The idle or busy test of the called subscriber, themetering, the transmission of the category are efiected in the same wayas for an ordinary subscriber by the final selector local part. At theconcentrators, there may be provided either lines grouped under the samenumber (PBX) or party lines; the way or" using a line may also bemodified. if distant concentrators have to be connected to existingexchanges, only slight modifications have to be carried out; finalselector frames similar to those already provided may be used; with theremoval of the talking wires and the addition of the equipments totransmit and receive the necessary information between exchange andconcentrator.

A further feature of the invention is the fact that when the localportion of the final selector is set on a position corresponding to thecalled subscriber of the concentrator, a send-receive device is put intooperation and sends to "ice 2 the concentrator the position informationof said local portion, said information being received on a send-receivedevice located at the concentrator and controlling the setting of thefinal selector distant portion on the called subscriber.

A further feature of the invention is the fact that when a subscriber ofa concentrator initiates a call, said subscriber is identified by anysuitable means and that the send-receive device of the concentratorsends to the sendreceive device of the exchange information character:izing the said subscriber, the position of this latter being then markedon the outlets of the final selector local portion and this markinginitiating the normal hunting process of the calling line, the finalselector local portion prescribing its position to the distant portion,following a procedure defined in the preceding feature.

A further feature of the invention is the fact that when the finalselector distant portion is set on a position corresponding to that ofthe local portion, i.e. on the subscriber, calling or called, saidsubscriber is connecwd to the exchange in the same Way as for a localsubscriber, tins arrangement allowing, besides other advantages,omission of the supply from the concentrator and the sending from theexchange of a supply current, the type of which permits selecting asubscriber among several subscribers of a party line.

A further feature of the invention is that the transmission ofinformation between exchange and concentrator may be carried out eitheron one of the junction circuits normally employed for the talking path,or on a special circuit provided for this case and that the junctioncircuit is chosen by a distributor located at the concentrator if theinformation is sent from the concentrator to the exchange, while ajunction circuit is chosen by the penultimate selector (call hunter orfifty selector) if the information is sent from the exchange to theconcentrator; as a result of this arrangement, two junction circuits,which are generally different, are successively called in case a subscriber of the concentrator initiates a call, one of the circuits beingused to transmit the identity of the calling subscriber to the exchangeand the other to send to the concentrator the position information ofthe final selector local portion.

A further feature of the invention is the fact that the send-receivedevices are busied only during the time strictly necessary to fulfilltheir :function, so as to reduce their number and the cost; of theplant, a simplified equipm nt (junctor) being provided at each junctioncircuit terminal for the seizure and clearing signals.

A further feature of the invention is the use of a marking equipment toremember the calling subscriber identification code in case of a callinitiated by the concentrator, allowing thus a quick clearing of thesend-receive device at the exchange, even it" the call cannot beextended immediately.

A further feature of the invention is the fact that after transmissionof the calling subscribers identity, from the concentrator to theexchange, the send-receive devices of the exchange and the concentratorremain in the busy condition of a new call initiated from theconcentrator, as long as the given call has not been extended, theditierent calls being thus successively extended.

A further feature of the invention is the fact that during the timewhich elapses between the setting of the final selector local portionand that of the distant portion, the line wires are looped at theexchange to keep the selection stages seized, so that if the callingsubscriber does not carry on with his call, the line Wires are openedafter the setting of the selector distant portion, which initiatesautomatically the clearing out of all the seized apparatus.

A further feature of the invention is the fact that the

1. A TELEPHONE SWITCHING SYSTEM COMPRISING AN EXCHANGE, A PLURALITY OFDISTANT CONCENTRATORS, EACH CONCENTRATOR COMPRISING A FINAL SELECTORHAVING A LOCAL PART LOCATED AT SAID EXCHANGE AND A DISTANT PART INCLUDING THE TALKING WIRES LOCATED AT A DISTANT POINT, SAID LOCAL PARTINCLUDING ALL THE ELEMENTS OF A FINAL SELECTOR EXCEPT SAID TALKINGWIRES, MEANS LOCATED AT SAID DISTANT PART FOR TRANSMITTING THE IDENTITYOF A CALLING LINE TO SAID EXCHANGE AND TO MARK THE POSITION OF SAID LINEON THE OUTLETS OF SAID FINAL SELECTOR LOCAL PART, AND MEANS FORTRANSMITTING FROM SAID EXCHANGE TO SAID FINAL SELECTOR DISTANT PARTSIGNALS RELATIVE TO THE POSITION OF SAID FINAL SELECTOR LOCAL PART, ANDMEANS RESPONSIVE TO SAID SIGNALS FOR SETTING SAID FINAL SELECTOR DISTANTPART ON A POSITION SIMILAR TO THE POSITION OF SAID LOCAL PART.